Device for governing the temperature of a heater head of a hot gas engine

ABSTRACT

In a hot gas Stirling cycle engine, the heating temperature is controlled by a servo-governed system which selects optimum airfuel mixture from a blower driven by the engine thereby also compensating for variations of blower performance.

United States Patent Hakansson [451 Jan. 14,1975

[ DEVICE FOR GOVERNING THE TEMPERATURE OF A HEATER HEAD OF A HOT GAS ENGINE Inventor:

[75] Sven Anders Samuel Hakansson,

Malmo, Sweden Kommanditbolaget United Stirling (Sweden) AB & (10., Malmo, Sweden Filed: May 3, 1973 Appl. No.: 356,775

Assignee:

[30] Foreign Application Priority Data May 5, 1972 Great Britain 20986/72 US. Cl. 60/524 Int. Cl. F23k5/00, F02g l/06 Field of Search 60/524, 39

[56] References Cited UNITED STATES PATENTS 2,611,234 9/1952 Horowitz 60 X/524 3,397,533 8/1968 Steiner et al 6O X/524 3,782,120 1/1974 Brandenburg 60/524 FOREIGN PATENTS OR APPLICATIONS 624,970 8/1961 Canada 60/524 Primary ExaminerMartin P. Schwadron Assistant ExaminerH. Burks, Sr. Attorney, Agent, or Firm-Laurence R. Brown [57] ABSTRACT In a hot gas Stirling cycle engine, the heating temperature is controlled by a servo-governed system which selects optimum air-fuel mixture from a blower driven .by the engine thereby also compensating for variations of blower performance.

4 Claims, 3 Drawing Figures PATENTEU 1 H975 3 859 ,794

SHEET 2 OF 2 DEVICE FOR GOVERNING THE TEMPERATURE OF A HEATER HEAD OF A HOT GAS ENGINE This invention relates to a device for governing the temperature of a heater head of a hot gas engine comprising a temperature-responsive element giving signals in accordance with the temperature of the heater head, a servo-motor governed by said signals and being connected to regulating means connected to a combustion air blower and governing the rate of delivery of combustion air from said blower, and means responsive to the rate of flow of combustion air from the blower being connected to a fuel-control valve for regulating the flow of fuel for combustion with the air delivered by said blower.

The object of the present invention is to provide an improved device of the above type ensuring a reliable operation and a quick response to changes in engine output causing little or no detrimental influence upon the exhaust emission of the engine, i.e., it should ensure the right ratio between air and fuel at any engine load.

According to the present invention this is obtained thereby that said means responsive to the rate of flow of combustion air comprises a vane movably arranged in said flow and offering constant resistance against said air flow while being moved in the direction of said air flow in proportion to the air flow, the fuel control valve being of such known type that the rate of fuel delivery is a direct function of the displacement of a part of the fuel-control valve, and a lever transmitting movements to this part from the said vane.

How the invention may be put into practice is described in more detail with reference to the accompanying drawing in which FIG. 1 schematically shows a hot gas engine provided with a device according to the invention,

FIG. 2 schematically another embodiment of the invention, and

FIG. 3 a view from above of the embodiment of FIG. 2.

Referring to FIG. 1 a hot gas engine has a housing 1 and a heater head 2 which is heated by a burner 3. The temperature prevailing at the heater head 2 is measured by a temperatureresponsive element 4 giving signals to an amplifier 5 energizing a motor 6 connected to a choke valve 7 mounted in an air inlet duct 8 of a centrifugal blower 9 driven by a pulley 10 mounted on the engine output shaft. At the delivery side of the blower 9 a disc-shaped vane 11 is supported at one end of a two-armed lever 12, the other end of which lever contacts a governing stem of a fuel delivery valve 13. Fuel is delivered from the valve 13 to the burner 3 at a rate which is a direct function of the displacement of the stem of the valve 13 by the lever 12.

The air delivered by the blower 9 is passed to the combustion chamber of the hot gas engine through a duct 14, and the rate of flow will cause a movement of the disc-shaped vane 11 which is a direct function of the rate of flow of this air.

The device shown in FIG. 1 will operate as follows:

In case the engine load is changed e.g. by changing the mean effective pressure of the working gas or by connecting the working gas charge with a dead volume of a different size the temperature affecting the temperature-responsive element 4 will immediately change. A corresponding signal from the element 4, through the amplifier 5 and motor 6 will cause a closing movement of the choke valve 7, or conversely a falling temperature will cause an opening movement of the choke valve 7.

If a closing movement of the choke valve 7 results in a decrease in the flow of air delivered by the blower 9, the vane 11 with lever 12 and the valve 13 will immediately cause a corresponding change in the rate of the fuel flow to the burner 3. Thus the rate of fuel supply will always be matched to the air supply being fed to the burner 3, ensuring maintenance of the most favorable proportion between fuel and air at any engine load.

It will be understood that the device described will operate independently of the engine load and of the system for governing the engine load. Thus if the engine load is kept constant, but the engine is running more slowly at a corresponding greater torque this will initially cause a lower speed of the blower 9. Consequently the amount of air delivered will decrease and so will the rate of fuel supply. However, this will cause a decrease of the temperature of the heater head and in turn cause an opening of the choke valve 7 and a corresponding higher rate of fuel supply.

The device shown in FIGS. 2 and 3 differs from that of FIG. 1 therein that the choke valve 7 has been arranged at the delivery side of the blower 9 at a location where a return conduit 15 is branched off from the duct 14 and connected to the suction side of the blower 9. The vane 11 has been arranged at the suction side of the'blower 9 near the air intake.

The drive connection between the engine I and the blower 9 is established by a belt drive in which the pulleys each consists of two in the axial direction relatively movable discs leaving a V-shaped opening between them for holding the belt. In one of the pulleys e.g. the pulley 10 the two discs are influenced in the direc' tion towards each other by a spring in a manner known per se not shown. The other pulley 16 consists of two discs the axial distance between which is determined by a centrifugally operated device responsive to the rotational speed. Even this element is known in the art and will not be described and shown.

The device described above and shown in FIGS. 2 and 3 will operate as follows:

A signal from the element 4 caused by a decrease in temperature of the heater head 2 will cause such movement of the valve 7 that the connection between the delivery side of the blower 9 and the duct 14 will open. Simultaneously the connection between the delivery side of the blower 9 and the return conduit 15 will close. This will cause an increase of air flow around the vane 11 and thus an increase in supply of air and fuel to the burner of the engine. The advantage of this arrangement is that the blower 9 will consume less power at reduced delivery rates.

The transmission between the engine output shaft and the blower may be designed so that at low engine speeds e.g. during starting-up the blower 9 will be able to deliver sufficient amounts of air. Thus any extra blowers for providing combustion air during starting-up will not be necessary.

What is claimed is:

l. A device for governing the temperature of a heater head of a hot gas engine having a combustion chamber comprising in combination a temperature-responsive element giving signals in accordance with the temperature of the heater head, a servo-system governed by said signals, regulating means including a combustion air blower governing the rate of delivery of combustion air from said blower operable by said servo-system, and means responsive to the rate of flow of combustion air from the blower including a fuel-control valve for regulating the flow of fuel for combustion with the air delivered by said blower, wherein said means responsive to the rate of flow of combustion air comprises a vane movably arranged in said flow to offer constant resistance against said air flow and to move in the direction of said air flow in proportion to the rate of flow and wherein the fuel control valve being of such known type that the rate of fuel delivery is a direct function of the displacement of a part of the fuel-control valve with a lever transmitting movements to this part from the said vane.

2. A device according to claim 1, characterized in that said blower is driven by the hot gas engine.

3. A device according to claim 2 characterized in that the transmission between the hot gas engine and the blower has a variable ratio causing comparatively higher blower speeds at low engine speeds.

4. A device according to claim 1, characterized in that the said combustion air flow regulating means comprises a three way valve governing the rate of flow of air delivery of the blower, a by-pass leading'to the suction side of the blower and a delivery duct leading to the combustion chamber of the hot gas engine.

* l l l 

1. A device for governing the temperature of a heater head of a hot gas engine having a combustion chamber comprising in combination a temperature-responsive element giving signals in accordance with the temperature of the heater head, a servosystem governed by said signals, regulating means including a combustion air blower governing the rate of delivery of combustion air from said blower operable by said servo-system, and means responsive to the rate of flow of combustion air from the blower including a fuel-control valve for regulating the flow of fuel for combustion with the air delivered by said blower, wherein said means responsive to the rate of flow of combustion air comprises a vane movably arranged in said flow to offer coNstant resistance against said air flow and to move in the direction of said air flow in proportion to the rate of flow and wherein the fuel control valve being of such known type that the rate of fuel delivery is a direct function of the displacement of a part of the fuel-control valve with a lever transmitting movements to this part from the said vane.
 2. A device according to claim 1, characterized in that said blower is driven by the hot gas engine.
 3. A device according to claim 2 characterized in that the transmission between the hot gas engine and the blower has a variable ratio causing comparatively higher blower speeds at low engine speeds.
 4. A device according to claim 1, characterized in that the said combustion air flow regulating means comprises a three way valve governing the rate of flow of air delivery of the blower, a by-pass leading to the suction side of the blower and a delivery duct leading to the combustion chamber of the hot gas engine. 